I've read two articles about booting Windows from external drives as opposed to a stock Bootcamp install. Here are the links:



The latter of the two seems more difficult, plus I do not have an external hard drive with USB 3 compatibility, so I think I would use the other one. Though I could just buy a new external drive...

Has anyone tried these methods? I want to make sure they're legitimate before I try them.

Thanks! :)

  • I tried the second link with a USB3 external drive. I could start the installation but I was stuck because it was unable to boot from the windows partition. Commented Oct 9, 2014 at 9:00
  • on my iMac 27" , with fusion drive, I'm running rEFInd boot manager to select between macOS High Sierra, Kali Linux & Windows 10.
    – CJ Dana
    Commented Jun 3, 2019 at 22:05

3 Answers 3


I'm not sure if you are still looking for an answer, but here it is:

I haven't tried those specific methods, but I have installed Windows 10 on an external hard drive. It should be the same, although you will need a Windows 7 iso image.

Step 1: Download a virtual machine to run Windows on. I used VMWare Fusion and used a 30-day trial.

Step 2: Search "windows 10 iso image" and click the first link from Microsoft. Download it.

Step 3: Open the VMWare application and upload the Windows 10 iso image onto it, and run Windows.

Step 4: Go on your virtual Windows and download WinToUSB from this: https://www.easyuefi.com/wintousb/.

Step 5: Find and download a Windows 7 iso image. The official Microsoft website has it, but you will need the product key you received when you first installed windows.

Step 6: Open the WinToUSB tool and upload the .iso image onto it, and choose which version to install. Connect your external drive to your Mac, make sure it connects to VMWare, and select it once it shows up on WinToUSB.

Step 7: Wait until the tool installs Windows 7 onto the external drive. While this is running, go to the Bootcamp app and ONLY download the Windows Support Software.

Step 8: Once the WinToUSB tool finishes installing, you can close out of VMWare by shutting down from the virtual Windows. The connected external drive should show up on your mac again, and drag the Windows Support Software folder into the drive.

You should now have an external drive with Windows 7 on it, and the Windows Support Software on it as well. You can boot from it by restarting and holding option and choosing the external drive. Use the Windows Support Software to install the correct Apple Drivers in the external drive when inside the Windows 7 boot.

This was the method that worked for me on an Early 2014 MacBook Air on High Sierra.


For info and future searches ... With steps identical or very similar to those mentionned in the 2nd tuto (BleeptoBleep) i managed to install Windows 8.1 on an external SSD /thunderbolt and a late 2015 iMac 5K 27 retina i7 4G but not Windows 7 due to a potential incompatibility (havent found out the reason) with hardware and/or OS El Capitan (boot disk not showing up after "Alt" start-up with W7 but OK while OK with W8). Managed W7 installation on an older 2014 MacBook with Yosemite OS though, also on another external drive also bypassing the BCA (bootcamp)


I managed to install a Windows 8.1 Pro on a Samsung Portable SSD T1 drive using the following instructions:


For this purpose, I used a Parallels Desktop virtual machine. Also, since my Windows image file contained a Install.esd file instead of a Install.wim, I had to replace the following command:

ImageX.exe /apply D:\Sources\Install.wim 1 E:


dism /apply-image /imagefile:D:\sources\install.esd /index:1 /ApplyDir:E:\

I admit that I do not know if the same procedure would work for Windows 7.

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